1. Field of the Invention
The present invention relates to a microelectromechanical system (MEMS) actuator and, more particularly, to a MEMS actuator that a cantilever piezoelectric actuator and a comb actuator are combined to perform dual shaft drive. The MEMS actuator can be used in a driving apparatus of an ultra-slim optical disk drive.
2. Discussion of Related Art
A conventional actuator used in an optical pickup driving apparatus is a voice coil motor (VCM) actuator including a magnetic circuit for applying a magnetic flux to a coil to generate a Lorentz force, a bobbin for fixing the coil and optical parts, a wire suspension for supporting the bobbin and damping vibrations transmitted to the bobbin, and a printed circuit board (PCB) for transmitting input and output signals of a servo system and supplying current to the coil. However, it is difficult to manufacture the conventional VCM actuator in an ultra-small size due to a structure that the bobbin for winding the coil, a support member for supporting the bobbin, and the magnetic circuit including a magnet, a yoke plate and so on should be required.
A single shaft control ultra-small actuator mainly uses a MEMS comb actuator or a cantilever piezoelectric actuator depending on purpose.
The comb actuator using an electrostatic force applies a voltage to a pair of combs perpendicularly projected from a planar surface and inserted into each other so that the electrostatic force generated between the two combs uniformly produces power depending on relative movement between the combs. The electrostatic comb-drive actuator has an advantage of providing uniform power with respect to movement of one comb.
The cantilever piezoelectric actuator is manufactured mostly using PZT ceramic, and used in various fields that a microscopic location control apparatus is required. This actuator has an advantage capable of readily performing precise control since displacement of the actuator is determined depending on a driving voltage applied to a piezoelectric material. In particular, it is possible to compose the ultra-fine actuator since its displacement can be controlled by tens of nanometers. The cantilever piezoelectric actuator has been used for obtaining and controlling ultra-fine driving force such as driving force of an atomic force microscope (AFM), a nano drive actuator, a MEMS structure and so on.
However, the conventional actuators have disadvantages that only single shaft can be controlled, its application range is limited, especially, the piezoelectric actuator should have high drive voltage in order to obtain large displacement using the PZT ceramic, and therefore, it is difficult to manufacture the actuators in a small size.